Warm white light is typically generated in that primary light emitted from an LED chip is at least partially converted into light of another wavelength by at least one phosphor, and the various fractions of light of different colors which are thus generated have a warm white total colorimetric locus. For example, blue primary light may be at least partially converted into red light by a “red” colorant and may be at least partially converted into green light by a “green” colorant. The resulting mixed light is red-green-blue or white, wherein a warm white color tone can be achieved, for example, by way of a high red fraction or by way of an additional wave conversion into a yellow or orange light.
However, in addition to the Stokes heat, still other losses also occur during the wavelength conversion. The phosphor can thus be embedded as a filler material (for example, powder) in a light-transmissive matrix material (for example, silicone). However, this may be less efficient, since the light power can be substantially reduced by the matrix material. An improvement of the efficiency is caused by so-called “local full conversion”. In this case, the green and/or yellow color fraction is generated by a ceramic lamina, which is very efficient. However, there are currently no ceramic laminae which emit red light. For the red color fraction, as has resulted from internal experiments which have not yet been published, a hole can be created in the ceramic lamina and filled with a mixture of silicone and red colorant. For suitable colorimetric loci, however, this hole must be so large that the ceramic lamina only still has a small edge. However, this causes worse stability of the ceramic lamina, and a large amount of material is additionally discarded during the production.